1. Field of the Invention
The present invention relates to automatic splitter shifting in a manually shifted compound transmission having a lever-shifted main section connected in series with an auxiliary splitter or splitter-and-range section. In particular, the present invention relates to a splitter control for transmissions of the type described for automatically implementing splitter shifts and/or splitter-and-range shifts during a manual lever shift.
2. Description of the Prior Art
Controller-assisted, manually shifted transmission systems are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,582,558; 5,755,639; 5,766,111; 5,791,189; 5,974,906; 5,989,155 and 6,015,366, the disclosures of which are incorporated herein by reference.
Compound transmissions having a range and/or combined range-and splitter-type auxiliary transmission section are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 4,754,665 and 5,390,561, the disclosures of which are incorporated herein by reference.
Transmissions having manually shifted main sections and automatically shifted splitter sections are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,435,212; 5,938,711; 6,007,455 and 6,044,721, the disclosures of which are incorporated herein by reference.
Compound transmissions having automatically implemented range shifting are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,911,787 and 5,974,906, the disclosures of which are incorporated herein by reference.
In certain controller-assisted, manually shifted transmissions, splitter shifts are automatically implemented and, during a lever shift, the splitter is shifted to neutral and retained in neutral until the main section is engaged in the position selected by the operator. The system controller must then determine if the splitter should be engaged/reengaged in splitter-high or splitter-low and command engagement of the appropriate splitter ratio.
In accordance with the present invention, a manually shifted compound transmission with a splitter or combined splitter-and-range auxiliary section is provided which will automatically shift the splitter section and/or automatically disengage and then reengage the splitter section during a lever shift. Logic rules are provided to determine which splitter ratio should be reengaged after the splitter is shifted to neutral during a manual lever shift.
The foregoing is accomplished in a manually shifted compound transmission having a lever-shifted main section connected in series with a splitter or combined splitter-and-range auxiliary section having an actuator for automatically implementing controller-initiated splitter shifts by sensing vehicle operating conditions, determining a target engine speed under such conditions, and engaging the splitter section in the splitter ratio which will result in an engine speed closest to the target engine speed. Preferably, the target engine speed will be midway between the upshift and downshift engine speeds for existing vehicle operating conditions. Preferably, a display and/or alarm or the like will be activated to inform the driver of the currently engaged ratio and/or splitter position.
Accordingly, it is an object of the present invention to provide a new and improved splitter shift control for manually shifted compound transmissions having a splitter shifter for automatically implementing splitter shifts.
This and other objects and advantages of the present invention will become apparent from a reading of the following description of the preferred embodiment taken in connection with the attached drawings.